Putrus, Raad, and Hamsa Saleem. “The Existence and Uniqueness of the Solutions for a System of Some Fractional Order Nonlinear Differential Equations”. Journal of Education and Science 21, no. 1 (March 1, 2008): 124–137. Accessed September 10, 2025. https://edusj.uomosul.edu.iq/index.php/edusj/article/view/41418.